Web drier and method of treating a web in continuous sheet printing machines

ABSTRACT

A web drier positionable between either the upper or lower runs of the relatively spaced web treating units of continuous sheet printing machines with the web drier having web heaters to dry the web and air appliers to break solvent laden fumes free of the web while air withdrawal means withdraw the applied air, and a method of treating the web to dry the same.

[4 1 June 6,1972

United States Patent Herbert, Jr.

[54] WEB DRIER AND METHOD OF TREATING A WEB IN CONTINUOUS SHEET PRINTING MACHINES ..34/l8 X .....34/l8 .34/18 X 2,186,032 2,559,713 Dunski et aL.

[72] Inventor:

William C. Herbert, Jr., Mill Neck, NY.

Primary Examiner-John J. Camby Attorney-Bauer 8L Amer Assignee:

Herbert Products, Inc., Westbury, N .Y.

[22] Filed: July 13, 1970 ABSTRACT [211 App]. No.:

A web drier positionable between either the upper or lower runs of the relatively spaced web treating units of continuous 52 US. 34/155, 263/3 Sheet Pfiming machines with the web having Web heaters to dry the web and air appliers to break solvent laden fumes free of the web while air withdrawal means withdraw the applied air, and a method of treating the web to dry the same.

[51] Int. 7/00, F27b 9/28 [58] Field of Search 8, 23, I55, 160; 263/3 15 Claims, 5 Drawing Figures PATENTEnJun 6 m2 SHEET 10F 3 INVENTOR WILLIAM C. HERBERT JR.

AT TORN E YS PATENTEDJUH 6 I972 SHEET 2 OF 3 INVENTOR WILLIAM C. HERBERT JR.

ATTORNEY PATENTEDJUH s 1912 SHEET 3 [IF 3 INVENTOR WILLIAM C. HERBERT JR.

awk-i M ATTORNEYS WEB DRIER AND METHOD OF TREATING A WEB IN CONTINUOUS SHEET PRINTING MACHINES This invention relates to web driers for use in continuous sheet printing machines and to a method of treating the web to dry the same.

The object of the invention is to provide a web drier that is so relatively inexpensive and compact as to be able to be positioned between relatively spaced web treating units or stations of continuous web printing machines wherever there is sufficient space for the same. Thus, in some printing machines, the web drier of the present invention may be positioned at the upper run or the lower run of the web as the same moves cont nuously through the many treating units of the printing macnme.

Another object of the invention is to provide a web drier which includes heating structures that may apply their heat to either one or both sides of the continuously moving web, and which, when during the operation of the printing machines it is necessary to terminate the application of heat to the web, the same is able to be accomplished without subjecting the web to the residual damaging heat of the heating structures.

Still another object of the invention is to provide a web drier which includes the application of air under pressure against one or both surfaces of the web to break through the solvent laden fumes that tend to statically adhere to the same to thereby enable the heating structures to perform their function more efficiently. I

A further object is the provision of an arrangement for the withdrawal or exhausting of air from about the web in such manner as to assure that the applied air and the solvent laden fumes broken free of the web are fully removed from about the web.

Still a further object is to provide a novel arrangement of structure which enables the operation of the heating structures to move into and out of a heat applying position.

A further object is to provide a novel method of treating a web that is continuously moving through a printing machine so as to effectively and efficiently dry the same.

The above description, as well as further objects, features and advantages of the present invention, will be more fully appreciated by reference to the following detailed description of a presently preferred, but nonetheless illustrative, embodiment in accordance with the present invention, when taken in conjunction with the accompanying drawings, wherein:

FIG. I is a side elevation of a continuous sheet printing machine illustrating the web drier positioned with respect to the same in accordance with the teaching ofthe invention;

FIG. 2 is a diagrammatic view of the web drier constructed according to the teaching of the invention;

FIG. 3 is an end view of the web drier with portions thereof broken away to illustrate internal structural details;

FIG. 4 is a view of FIG. 3 taken along lines 4-4; and

FIG. 5 is a view of FIG. 3 taken along lines 5-5.

Referring now to the drawings and in particular to FIG. 1, the printing machine there shown is generally identified by the numeral 10. The printing machine usually includes a plurality of sheet treating or printing stations generally identified by the numeral 12 through which a continuous web or sheet of material moves for treatment at the various stations of the machine. The web or continuous sheet is illustrated in dash lines and is identified by the numeral 14. The details of the printing machine 10 do not enter into any of the novel features of the present invention other than that the invention is able to be more easily utilized in connection with such printing machines by placing them fixedly in position on the printing machine. This may be done either between the upper run of the web 14 as the same moves between the treating units 12 or at the lower run of the printing machine generally beneath the catwalk 16 found in most printing machines between the stations 12.

Basically, the web drier of the present invention contains the same or substantially the same structural features whether the drier is positioned at the upper run of the web 14 as the same moves between the treating units 12 and as illustrated in the drawings or at the lower run of the web where the same moves beneath the catwalks 16 in a manner not shown but which will be obvious to those skilled in the art. Thus, for the sake of brevity and convenience of understanding, further details of the printing machine 10 will not be considered important and, therefore, a description of the same will be avoided as superfluous.

The web drier of the present invention is generally identified by the numeral 18. Any number of such web driers may be utilized in a multi-unit printing machine. This is illustrated more particularly in FIG. 1 wherein two such web driers 18 are shown. The web drier may be positioned in the space and intermediate the run of the web between the treating units of the printing machine when it is necessary to dry whatever material, print or other treatment to which the web has been subjected by a prior treating unit 12 of the machine. The web drier 18 comprises a heater housing generally identified by the numeral 22, the details of which are more fully illustrated in FIGS. 3, 4 and 5. 1 The heater housing 20 includes oneor more heater elements 24, each of which extends transversely across the full width of the web 14. The heater elements 24 are in the form of linear heaters which are encased in a cover 26, one side of which is open and the remaining walls of which cover and shield against the heat produced by the elements 24 from radiating in a direction other than outward from the cover opening. The heater arrangement is depicted more clearly in FIGS. 4 and 5 wherein a plurality of heater elements 24 are shown positioned within the housing 20 on opposite sides of the web 14 that moves through the printing machine in the direction of the arrow A. The heater elements 24 are arranged in two sets, each of which is relatively spaced from the other to form a path defined between them to provide for the movement of the web in the direction of the arrow A through the heater housing 20.

The heat from either the upper set or the lower set of heater elements 24 may be selectively controlled and directed selectively to either the upper or the underside of the web 14 moving through the heater housing 20 or in such manner that both sets of heater elements may be operated simultaneously to heat both sides of the web as the same moves in its path through the housing 20. The number of heater elements 24 utilized in the web drier 18 is not material, but rather, is controlled by the length of time that it takes the web to travel through the drier 18 and the amount of heat that must be applied to the web in order to properly dry the same within the available time period. Thus, although five heater elements 24 are illustrated in each set at the upper and underside of the web 14, this number is not controlling but rather illustrative of the invention.

The heater housing 20 includes side walls 28 and 28a which are secured together by cross rods 30. The heater housing 20 is enclosed at the top thereof by a shielding frame 32 which includes insulating shielding members 34 strategically positioned thereabout to prevent the possibility of the heat generated within the heater housing from radiating outwardly beyond the same or from dissipating toward areas that might possibly do damage to adjacent portions of the printing machine 10 and to the web 14 moving therethrough. Thus, the arrangement of the shielding members 34 and of the frame 32 may be varied depending upon the location in which the web drier 18 is positioned on or within the printing machine 10. However, it will be noted that for convenience of illustration and more especially in FIGS. 3 and 4, the shielding members 34 overlap each other to a sufiicient and substantial extent so that the heat generated by the heater elements 24 will not radiate beyond the housing 20.

The heater housing 20 is connected to the linkage housing 22 in any convenient manner. In the drawing of FIG. 3, this is accomplished by the use of U-shaped brackets 36 which secure the housings together. Additional bridging supports 38 also may be provided if the same are required. The linkage housing 22 encloses an actuating linkage mechanism to be described. However, to afford access to the interior of such housing, the same is provided with a side wall 40, opposite end walls 42 and a removable cover access door 44.

The heater housing 20 also includes a plurality of air applying means 46 which are mounted fixedly within the heater housing in alternate spaced relation with each of the heater elements 24. Interspaced alternately between each heater element 24 is an air applying means 46 in the form of a pipe or other tubular structure. Since there are two sets of heater elements 24, one positioned above the web 14 and the other along the underside of the web 14, there are also two sets of air applying means 46 similarly positioned above and along the underside of the web. Each of the air applying means extends for the full width of the web 14 such that the air that is forced out of appropriate nozzles 48 (not shown) of the applying means 46 under pressure will fully cover that surface of the web against which the air is applied.

For convenience, and to assure the proper operation of the air applying means 46, the same extend fully transversely between the'side walls 28 of the heater housing 20 and the exhaust nozzles 48 defined in such air applying means 46 similarly apply air transversely across the full width of the heater housing as defined between the walls 28. It will be noted in the drawing that the direction of the air emitting under pressure from the exhaust nozzles 48 of the air applying means 46 is at an angle to the adjacent surface of the web 14 and that this angle is fixed since the air applying means also are fixed in position within the heater housing 20. The angle at which the air exhausted from the nozzles 48 of the air applying means strikes the adjacent surface of the web 14 is approximately 30 to the vertical so as to function in the. manner of a knife which acts in a direction opposite to the movement of the web as shown by the arrow A.

This knife-like action of the air exhausting from the noules 48 from the air applying means 46 in the direction of the arrows (48) attacks the surface of the paper under such pressure as to break loose all solvent laden fumes that tend to statically adhere to the surface of the web after the same has been treated in the prior treating unit 12 of the printing machine. These solvent laden fumes tend to adhere to the web and it is necessary to attack them with a strong air pressure from the air applying means'46 to break them free of the web surface 14. Since the air applying means are positioned to act on opposite sides or surfaces of the web, it is unimportant whether the web has been treated in the prior station 12 of the printing machine on one or both sides, such solvent laden fumes that may tend to adhere to any surface of the web are broken loose and lifted free. By removing the solvent laden fumes from the web, the heater elements are enabled to direct their heat directly upon the treated surfaces of the web rather than having to penetrate through the solvent laden fumes before they can effectively dry the treated surface of the web. Thus, the loosening and elimination of the solvent laden fumes from adherance to the web surfaces results in a quicker and more efiicient drying of the web.

Oftentimes it is necessary during the operation of the printing machine to stop the movement of the web through the machine. When this happens, it is necessary also to terminate the operation of the heater elements 24. Otherwise, the heat that they may continue to generate, even though such heat is a residue after the heater elements are de-activated or turned ofi, will damage the surface of the web that is stopped within the drier. To prevent possible damage to the web, the present invention provides a unique arrangement for pivotally moving the heater elements 24 into and out of their heat applying position. Referring to FIGS. 4 and 5, the heater elements 24 shown in solid lines are in position to apply their heat to the adjacent surface of the web 14.

Those heater elements shown in dash or broken lines have been pivoted substantially a full 90, such that whatever heat is generated by the heater elements or whatever residual heat may be generated by the heater elements 24 after their operation has been terminated will not be directed toward the surface of the web, but rather, will be directed away from the surface of the web. Thus, each heater element 24 has an operative or heat applying position as shown in solid lines and an inoperative position 90 or normal to the adjacent surface of the web as shown in dash lines. When in the inoperative position, the heater elements are sufiiciently shielded by their heater covers 26 to obviate the possibility of directing their residual heat to the web surface.

In order to pivotally move the heater elements from their operative heating positions to their inoperative non-heating positions, each such element 24 is conveniently mounted at one of their ends on a simple pivot, not shown, but at their opposite ends within a substantially U-shaped bracket 50, the details of which may be conventional and, therefore, are diagrammatically shown in FIG. 3. Each bracket 50 is connected with a rotatable coupling 52 which is rotatably supported and mounted in the adjacent side wall 28. The coupling 52 is mounted on a shaft that is fixedly connected for rotative movement with a respective link 54 at a connection 55 seen more clearly in FIG. 5. Each link 54 is connected to a cross bar 56 at a pivotal mounting 57. Each cross bar 56 is connected by a pin 58 in a loss motion connection slot 60 of an operable pivot lever 62 mounted in housing 22 for pivotal movement at 64.

The operating lever 62 is connected at one of its ends to an actuator 66 that may be remotely operated hydraulically as by an hydraulic cylinder 68 having selectively operable actuator hydraulic lines 70 connected thereto. When the hydraulic cylinder 68 is actuated in response to the movement of fluid through one of the lines 70, the operating lever 62 is pivoted causing linear movement of the cross bars 56 and the consequent pivoting of each of the links 54 connected therewith to pivot about the axis of the connections 55. In turn, rotate the respective couplings 52 and their brackets :50 correspondingly rotate the respective heater elements 24 between their operative heat applyingposition and the inoperative position. It will be noted that because of the arrangement of the cross bar connections 56 with the operating lever 62, all heater elements 24 are simultaneously moved into or out of their heat applying position, thereby assuring that no one heater element will remain in its heat applying position while the other elements are moved out of such position.

The interspaced relationship of the air applying means 46 between the heater elements 24 permits the continuous application of air to the web whether or not the heater elements 24 are in their active heat applying position. Thus, as long as air is being supplied under pressure to the air applying means 46, the same will be applied under pressure directly to the adjacent surface of the web. Air issupplied to the air applying means by way of an air supply pump 72 shown in FIG. 1. In the embodiment of FIG. 1, the air supply pump 72 is mounted above and on top of the heater housing 20 and is connected with suitable air conveying conduits 74 that conduct the air from the pump to the air applying means 46.

However, in FIG. 2 and in the construction shown in FIG. 3, the air conveying conduits 74 are extended in length and are joined with a main supply conduit 75 which serves to connect the same with the air supply pump 72 that is located and mounted in a position remote from the heater housing 20. Thus, the arrangement of FIG. 1 illustrates one possible feature of the invention while the arrangement of conduits and the location and mounting of the air supply pump 72 as shown in FIGS. 2 and 3 illustrates another possible manner of mountmg.

Since the air supply pump 72 is connected directly by the conduits 74 with the air applying means 46 which discharge their air under pressure against the adjacent surfaces of the web 14, it is necessary to assure that all of the solvent laden fumes broken free of the web surface are removed from the heater housing. If such fumes are not removed, they tend to remain suspended in the air within the heater housing 20 and thus reduce the efficiency and effectiveness of the heater elements. In the present invention, an air withdrawal or exhaust structure is provided in the form of an air exhaust pump generally identified by the numeral 76.

The air exhaust pump 76 is connected with an air exhaust conduit 78 that will be seen to be larger in size than that of the inlet or supply conduit 75 and, therefore, its capacity is much greater. The conduit 78 is connected with the heater housing 20 at the side wall 28A. The details of such connection are not shown. However, in referring to P16. 4, it will be noted that the side wall 28 is provided with an opening 80. A similar opening 80 is defined in the opposite side wall 28A and the exhaust conduit 78 is connected to such'similar opening 80 by a manifold that is not shown. Because of the larger capacity of the air exhaust pump 76 and the larger volumetric capacity of the conduit 78 connected therewith, the operation of the exhaust structure will remove relatively greater amounts of air from the interior of the heater housing 20 than is supplied to the same by way of the air supply pump 72.

In practice, the air exhaust structure will exhaust air from completely about the web 14 as the same moves through the space defined by the upper and lower set of heater elements 24. It removes solvent laden fumes from the heater housing 20 at a rate far greater than that at which the air is supplied to the heater housing bythe air inlet or supply means 72. This assures that all free solvent laden fumes are completely removed from the housing 20. This relatively greater exhaust structure also functions to remove air in excess of the air supplied to the housing by the supply means 72. By so doing, it further aids in the lifting and breaking free of the solvent laden fumes from the web 14., Thus, the action of the air pressure applying means 46 is supplemented by the excess exhaust capacity of the air exhaust means 76.

It has been noted that the heater elements 24 may be operated such that either the upper or underside set of heater elements positioned on opposite sides of the web may be selectively controlled. This may be accomplished by connecting the heater elements to a selective switch panel not shown. The switch panel is wired to the heater elements by connecting each heater element with a bus bar 82 and a ground connection 84. The wiring may be completed through wiring ducts 86 that extend into wiring boxes 88 positioned on the side of the heater housing 20 remote from that of the linkage housing 22; The precise location of the wiring boxes 88 and the connections 82 form no part of the invention. One of the boxes 88 has had its cover removed to illustrate the connections while the other box 88 is closed by securing means 90.

Because the web drier 18 may be mounted conveniently at the upper run of the web 14 in the spaces between the treating units 12 of the printing machine 10, any convenient form of mounting structure may be provided. One such arrangement is illustrated in FIG. 1 wherein angled supports 92 are mounted by legs 94 above the printing machine frame 96. This mounting arrangement is shown in greater detail in FIG. 2 wherein there may be provided adjustment mechanisms 98 to permit the raising and lowering of the entrance or exit ends of the drier structure 18 with respect to the machine frame 96. In FIG. 4 the heater housing 20 is shown with overhead brackets 100, the details of which form no part of the invention but which may be utilized to conveniently mount the air supply pump 72 above the heater housing 20 in the mariner shown in FIG. 1.

In utilizing the present invention, the web 14 usually moves continuously through the relatively spaced multiple printing or treating units 12 of the printing machine 10. It is immaterial whether the present inventive drier 18 is mounted at the upper or lower run of the web. However, in drying the web, the surface thereof is subjected to the heat of the heaterelements 24. Thus, if it is desired to heat just one treated surface of the web, the heater elements facing that surface maybe operated while the heater elements facing the untreated surface may be left inoperative.

As the web moves through the path defined about the upper and lower sets of heater elements, it is subjected to the high pressure stream of air provided by the air supply pump 72. An air applying means is positioned between each heater element 24 to assure that there is an alternate heating and high air pressure breaking of the solvent laden fumes to free them from the surface of the web. This alternate heating and application of air pressure to the treated surface of the web is performed simultaneously for the maximum drying benefit. During such heating and simultaneous application of air pressure to the treated web surface,the web is further simultaneously subjected to an air exhaust of greater capacity than that of the air supply thereby aiding the air supply in lifting the fumes free of the web and fully and completely withdrawing such fumes from about all surfaces of the web, including the untreated surfaces.

Even at times when the machine is shut down or when the heater elements 24 are actuated from their operative position to their inoperative position, the air supply is continued and the air exhaust is maintained so that whatever residual heat might possibly tend to come into contact with the web surface will be prevented from impinging upon the web by the high pressure stream of air supplied by the air applying means and such heat will be quickly withdrawn from the heater housing 20 by the air exhaust means. Thus, the application of air and the withdrawal of air from about the web continues independently of the operation of the heater elements to assure that the web remains unafiected and undamaged by possible residual heat that might accidentally tend to impinge upon the web surfaces.

While there have been shown and described and pointed out the fundamental novel features of the invention as applied to a preferred embodiment thereof, it will be understood that various omissions and substitutions and changes in the form and details of the deviceillustrated and'in its operation may be made'by those skilled in the art without departing from the spirit of the invention. It is the' intention, therefore, to be limited only as indicated by the scope of the claims appended hereto.

' WHAT IS CLAIMED IS:

1. In a printing machine having a plurality of relatively spaced web treating units,

a drier positioned between said relatively spaced web treating units to dry the web as the same moves through the space between said units,

said drier including means to heat the web as it moves through the space between said units, means applying air to said web to break solvent laden fumes free from the web as the web moves through the space and means to exhaust the air from about the web as it moves through the space,

and said exhaust means having an air exhausting capacity in excess of said air applying means withdrawing air from about said web at a rate in excess of the supply of said air applying means.

2. In a printing machine as in claim 1,

said web having an upper run of movement from one to another of said plurality of relatively spaced units,

and mounting means on said drier to mount the same to the printing machine between said relatively spaced units at the upper run of said web.

3. In a printing machine as in claim 1,

said web having a lower run of movement from one of said plurality of relatively spaced units to another,

and means on said drier to mount the same to said printing machine between said relatively spaced units at the lower run of said web.

4, In a printing machine as in claim 1, 7

said heat means being movable to and from a position to heat the web during its movement through the space,

and means operable to move said heat means to and from said heat position.

5. A web drier for a continuous web moving through a printing machine comprising a plurality of heater elements each having a position to apply heat to the moving web,

said heater elements extending transversely across the ef fective width of the web and relatively spaced from each other in the direction of the movement of the web through the printing machine, i

said heater elements being rotatable into and out of their position to apply'heat to the moving web,

and operable means connected with said heater elements to rotate the same into and, out of their heat applying position,

means to apply air to said web transversely across the heated width thereof, v

means to supply airto said air applying means,

and means to withdraw air from about the web at a rate in excess of the capacity of said air supply means.

6. A web drier as in claim 5, i

said web drier including sets of said plurality of transversely extending relatively spaced heater elements with a path defined between said sets for the movement of the web in said path between said sets for the application of heat to the opposite surfaces of the web,

and said operable means being connected with each of said sets of said heater elements to move each of said heater elements substantially simultaneously into and out of their heat applying position.

7. A web drier as in claim 6,

said air applying means being in the spaces between said relatively spaced heater elements.

8. In a web drier for a continuously moving web,

means for heating at least a surface of the web,

said heating means having a first position wherein the heat thereof is directed at the surface of the web and a second position wherein the heat thereof is directed away from the surface of the web,

air applying means to apply air under pressure to remove solvent laden fumes from the web,

air supply means to supply air under pressure to said air applying means,

and air exhaust means having a capacity in excess of said air supply means and the air applied to the web by said air applying means to remove all of the applied air from about the web.

9. in a web drier as in claim 8,

said heating means being a plurality of heater elements relatively spaced from each other along a portion of the length of the direction of movement of the web,

and said air applying means being a plurality of elements relatively spaced from each other along a portion of the length of the direction of movement of the web with each of said heating means and air applying elements being alternately arranged along the direction of movement of the web. i

10. In a drier as in claim 9, 1

a housing mounting said heating means and air applying means and including shielding means to obstruct the heat of said heating means from passage beyond said housing when said heating means are in theirheating'position.

11. In a drier as in claim 9,

and operable means connected with each of said hater elements to move 'the same between their first and second positions,

said operable means including a pivoted lever,

an actuator connected with said lever to pivot the same,

a bar movable in response to the pivoting of said lever,

and a plurality of links connected with said bar for rotation thereby, 7

each of said links being connected with a respective one of said heating means to rotate the same simultaneously between said first and second positions in response to the pivoting of said lever by said actuator.

12. In a drier as in claim 11,

said heating and air applying means being arranged in sets along opposite surfaces of the moving web.

13. The method of treating a web continuously moving through relatively spaced multiple printing units of a printing machine comprising subjecting a surface of the web to direct heat and a high pressure stream of air as the same moves through at least one of the spaces between the multiple printing units while simultaneously subjecting the area about the web to an air exhaust of greater capacity than the amount the air to which the web is subjected to fully withdraw all of the high pressure air from about the web.

14. The method as in claim 13, simultaneously subjecting the web to heat and a high pressure stream of air alternately along the direction of movement of the web andon opposite surfaces thereof. 15. The method as in claim 13, and directing the heat away from the web surface while continuing to subject the same to a high pressure stream of air and to the relatively greater air exhaust. 

1. In a printing machine having a plurality of relatively spaced web treating units, a drier positioned between said relatively spaced web treating units to dry the web as the same moves through the space between said units, said drier including means to heat the web as it moves through the space between said units, means applying air to said web to break solvent laden fumes free from the web as the web moves through the space and means to exhaust the air from about the web as it moves through the space, and said exhaust means having an air exhausting capacity in excess of said air applying means withdrawing air from about said web at a rate in excess of the supply of said air applying means.
 2. In a printing machine as in claim 1, said web having an upper run of movement from one to another of said plurality of relatively spaced units, and mounting means on said drier to mount the same to the printing machine between said relatively spaced units at the upper run of said web.
 3. In a printing machine as in claim 1, said web having a lower run of movement from one of said plurality of relatively spaced units to another, and means on said drier to mount the same to said printing machine between said relatively spaced units at the lower run of said web.
 4. In a printing machine as in claim 1, said heat means being movable to and from a position to heat the web during its movement through the space, and means operable to move said heat means to and from said heat position.
 5. A web drier for a continuous web moving through a printing machine comprising a plurality of heater elements each having a position to apply heat to the moving web, said heater elements extending transversely across the effective width of the web and relatively spaced from each other in the direction of the movement of the web through the printing machine, said heater elements being rotatable into and out of their position to apply heat to the moving web, and operable means connected with said heater elements to rotate the same into and out of their heat applying position, means to apply air to said web transversely across the heated width thereof, means to supply air to said air applying means, and means to withdraw air from about the web at a rate in excess of the capacity of said air supply means.
 6. A web drier as in claim 5, said web drier including sets of said plurality of transversely extending relatively spaced heater elements with a path defined between said sets for the movement of the web in said path between said sets for the application of heat to the opposite surfaces of the web, and said operable means being connected with each of said sets of said heater elements to move each of said heater elements substantially simultaneously into and out of their heat applying position.
 7. A web drier as in claim 6, said air applying means being in the spaces between said relatively spaced heater elements.
 8. In a web drier for a continuously moving web, means for heating at least a surface of the web, said heating means having a first position wherein the heat thereof is directed at the surface of the web and a second position wherein the heat thereof is directed away from the surface of the web, air applying means to apply air under pressure to remove solvent laden fumes from the web, air supply means to supply air under pressure to said air applying means, and air exhaust means having a capacity in excess of said air supply means and the air applied to the web by said air applying means to remove all of the applied air from about the web.
 9. In a web drier as in claim 8, said heating means being a plurality of heater elements relatively spaced from each other along a portion of the length of the direction of movement of the web, and said air applying means being a plurality of elements relatively spaced from each other along a portion of the length of the direction of movement of the web with each of said heating means and air applying elements being alternately arranged along the direction of movement of the web.
 10. In a drier as in claim 9, a housing mounting said heating means and air applying means and including shielding means to obstruct the heat of said heating means from passage beyond said housing when said heating means are in their heating position.
 11. In a drier as in claim 9, and operable means connected with each of said hater elements to move the same between their first and second positions, said operable means including a pivoted lever, an actuator connected with said lever to pivot the same, a bar movable in response to the pivoting of said lever, and a plurality of links connected with said bar for rotation thereby, each of said links being connected with a respective one of said heating means to rotate the same simultaneously between said first and second positions in response to the pivoting of said lever by said actuator.
 12. In a drier as in claim 11, said heating and air applying means being arranged in sets along opposite surfaces of the moving web.
 13. The method of treating a web continuously moving through relatively spaced multiple printing units of a printing machine comprising subjecting a surface of the web to direct heat and a high pressure stream of air as the same moves through at least one of the spaces between the multiple printing units while simultaneously subjecting the area about the web to an air exhaust of greater capacity than the amount the air to which the web is subjected to fully withdraw all of the high pressure air from about the web.
 14. The method as in claim 13, simultaneously subjecting the web to heat and a high pressure stream of air alternately along the direction of movement of the web and on opposite surfaces thereof.
 15. The method as in claim 13, and directing the heat away from the web surface while continuing to subject the same to a high pressure stream of air and to the relatively greater air exhaust. 